Background Full femtosecond laser refractive surgery has been generally applied,but the improvement of visual quality after surgery is a vital problem.It is well-known that modulation transfer function (MTF) is a major evaluation indicator.Objective To investigate the change of the MTF of operated eyes after the full femtosecond laser refractive surgery.Methods A retrospective series of cases study was adopted.Forty eyes of 23 patients with the spherical equivalent of-2.25 to-5.75 D who received full femtosecond laser refractive surgery were enrolled in Nanjing General Hospital of Nanjing Military Command from July to October,2012.The change of visual acuities was analyzed and compared among before operation and 1 day,1 week and 1 month after operation.MTF value in total aberration,low and high order aberrations under the 3.0 mm and 6.0 mm pupil size conditions were detected with i-Trace Visual Function Analyzer at above time points.The MTF values among various time points,between different pupil diameters and different spatial frequencies (5,10,15,20,25 c/d) were compared respectively.Results Compared with the preoperation,the visual acuity improved in postoperative 1 day,1 week and 1 month,showing a significant improvement among various time points (F =10.341,P =0.000).Corrected diopter was 3.795 D at average.MTF values under the 3 mm pupil diameter gradually elevated with the lapse of time after operation,without significant differences among different time points whatever total aberration,low and high order aberrations(all at P＞0.05).The MTF values under 6 mm pupil diameter of total aberration and low order aberration were significantly higher in postoperation than those in preoperation(all at P＜0.05),but no significant difference was seen in MTF of high order aberration among various time points (F =0.260,P =0.854).Compared with the MTF under the 3 mm pupil diameter,those of low and high order aberrations under the 6 mm pupil diameter considerably declined in preoperation and postoperative 1 month (preoperation:P =0.050,0.001 ; postoperation:P =0.012,0.001).MTF values under the 3 mm pupil diameter were not different at various spatial frequencies (all at P＞ 0.05).However,MTF values under the 6 mm pupil diameter were gradually increased from preoperation through postoperative 1 month at 10,15,20 and 25 c/d (P =0.044,0.043,0.024,0.014).Conclusions Full femtosecond laser refractive surgery can eliminate low aberration,increase the MTF and acuity,and therefore improve the visual quality.MTF is one of the key indicators assessing visual quality after full femtosecond laser refractive surgery.%背景 全飞秒激光辅助的屈光手术已广泛用于临床,其术后术眼视觉质量的改善情况是临床医师关注的主要问题.调制传递函数(MTF)是评价视觉质量的主要指标. 目的 研究近视患者行全飞秒激光屈光手术后在明暗条件下(3 mm或6 mm瞳孔直径)MTF的变化,以评价术后的早期视觉质量. 方法 采用回顾性系列病例观察的研究方法,选取2012年7-10月在南京军区南京总医院行全飞秒激光屈光手术的中低度近视[等效球镜度(SE)为-2.25 ～-5.75 D]患者23例40眼作为研究对象,分析并比较术眼术前及术后1d、1周、1个月的视力变化;用i-Trace视功能分析仪测量术眼3 mm和6 mm瞳孔直径下术前及术后1d、1周、1个月总像差、低阶像差和高阶像差的MTF值,比较3 mm和6 mm瞳孔直径间不同像差MTF的差异.分别对瞳孔直径3 mm或6 mm时在最佳矫正视力(BCVA)状态下测量的术前及术后1d、1周、1个月间在5、10、15、20、25 c/d空间频率下的MTF值进行比较. 结果 与术前裸眼视力和BCVA比较,术眼术后1d、1周、1个月的视力逐渐提高,各时间点间视力的比较差异有统计学意义(F=10.341,P=0.000);术眼术后屈光度平均矫正量为3.795 D.术后1d、1周、1个月,3 mm瞳孔直径下总像差、高阶像差和低阶像差下MTF值随时间的延长均有升高的趋势,但差异均无统计学意义(P＞0.05).6 mm艟孔直径下术后各时间点总像差、低阶像差下MTF值明显高于术前,差异均有统计学意义(P＜0.05),而术前及术后各时间点高阶像差MTF值的变化差异无统计学意义(F=0.260,P=0.854).与3 mm瞳孔直径下比较,术眼术前及术后1个月6 mm瞳孔直径下低阶像差和高阶像差的MTF值明显下降,差异均有统计学意义(术前:P=0.050、0.001;术后:P=0.012、0.001).3 mm瞳孔直径下各空间频率的MTF值差异均无统计学意义(均P＞0.05),而6 mm瞳孔直径下各时间点10、15、20、25 c/d空间频率下MTF值随着术后时间的延长均逐渐升高,差异均有统计学意义(P=0.044、0.043、0.024、0.014). 结论 全飞秒激光近视屈光手术能够消除低阶像差,术后MTF值明显提高,患者裸眼视力提高,从而改善患者的视觉质量.应用MTF值能够客观地分析全飞秒激光近视屈光手术后视觉质量的变化.
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